As described in our above-referenced application, there have been many suggestions made to improve keyboarding efficiency in typewriter and typewriter-like devices. In addition to the prior art mentioned in the above-identified application, there have also been suggestions for devices to automatically verify the spelling of text input through a keyboard. A particular disadvantage of most such devices is the relatively vast amount of storage required, and several recent suggestions, such as those disclosed in U.S. Pat. Nos. 3,925,761 and 3,995,254, evidence an effort to reduce the required amount of storage.
The addition to the typewriter (which is itself about 100 years old), of the intelligence afforded by programmed digital computers, and even more recently by the microprocessor, allows a vast improvement in the intelligence of the device without significantly increasing the space it occupies since the microprocessor itself and its related storage devices can easily be enclosed in otherwise unused spaces within a typewriter casing.
Electronic typewriters, i.e., typewriters including digital processors, on the market today generally are comprised of three basic components. A first component is the keyboard itself which generally has an appearance similar to other conventional typewriters in that the layout of the alphanumeric keys is standard, although it may have a few additional function implementing keys. In contrast to the earlier mechanical or electro-mechanical typewriters, the function of the keyboard in the modern electronic typewriter is merely to generate a unique signal in dependence upon a particular key actuated by an operator. This signal sometimes called the keycode, is then presented to the electronics, which is the second major component in the typewriter. The function of the electronics is to interpret the keycode in order to generate character or function identifying signals which are fed to the third component, i.e., the display mechanism for the generation of alphabetic symbols, numerical symbols, punctuation marks, other graphic symbols, and the functions necessary to relate these symbols. These various symbols must be related in a format which is easily understood by a reader and this requires such functions as spacing between different symbols, spacing between words, spacing between lines, and locating symbols in an ordered sequence as determined by the operator's actuation of the various keys on the keyboard. The particular form which the character and function identifying signals take depends in large part on the form of the display or output mechanism. For example, in those typewriters which include a print ball, the character identifying signals must be such as to cause the ball to rotate and tilt to the proper orientation to locate the desired character with respect to the printed page so that when the ball is impacted, the desired character symbol will be produced. On the other hand, in those typewriters employing an ink jet printer, the character and function identifying signals may take on different characteristics, and the same character and function identifying signals for use with the CRT or the like display possess still other requirements. Inasmuch as the present invention can be employed with all of these, and other equivalent output devices, the specific form of the character and function identifying signals will not be detailed here as they are well known to those skilled in the art.
In large part, the electronic typewriter mimics the function of the electromechanical or mechanical typewriter. More particularly, in the mechanical typewriter, the operator's actuation of a specific key produced the combination of mechanical movements which resulted in a type bar carrying an image of the character associated with the actuated key impacting a type ribbon onto a page to produce an image of that character and to also allow the paper carrying carriage or a movable print carrier to be displaced so that a next character is printed adjacent the previously printed character. In other words, this mechanical typewriter translated the operator's actuation of a specific key to a specific set of mechanical movements to produce the desired image. Similarly, the electronic typewriter translates the keycode generated by the operator's actuation of the key in the keyboard to those signals necessary to produce the desired image from the particular display device being driven.
However, with the intelligence added to the typewriter by the digital processor, additional functions can be implemented; one important function is the buffering between input and output provided by a storage device contained in the electronics. Thus, most electronic typewriters include a buffer into which the keycode is stored, and sequential key actuation result in the storage of sequential keycodes identifying the keys and the sequence in which they are actuated. The output device is then driven sequentially from the keycodes read from storage and translated through the medium of a storage table correlating keycodes and character or function identifying signals.
Hereinafter when referring to electronic typewriters we use the term as equivalent to a text recorder in that "typewriter" no longer carriers the implication of a machine necessarily requiring "type" to produce a text record. By text recorder we mean any device which produces a record (whether or not permanent) of a series of text characters and symbols interrelated to convey meaningful information to a human reader.
The referred to application discloses how, under certain circumstances, the actuation of a single key can be decoded into a string of character signals, so that actuation of a single key can produce a multi-character output. The referred-to application further discloses how, under certain circumstances, the particular multi-character output produced by the actuation of a specific key can be varied. One feature of the invention disclosed in the referred-to application is that of producing a first multi-character string upon the first actuation of a specific key, and producing a second multi-character string on a second sequential actuation of the identical key. Another feature of the invention disclosed in the referred-to application is that of producing a first or second single or multi-character string upon the actuation of a specific key in dependence upon the identity of a key actuated prior to the specific key. In the context of the referred-to application, this feature allowed the multi-character text recorder to output either a suffix or a word; the suffix was produced if the previously entered key was a character and the word was produced if the previously enetered key was a function such as a space or carriage return.
The present invention is arranged to solve a related but slightly different problem and to assist in both improving keyboard efficiency by generating a multi-character signal string in response to actuation of a single key, and at the same time, insuring the correctness of the spelling of the words so typed. In particular, many word endings sound the same but are spelled differently. For example, the word endings having the sound "ceed" can be spelled "sede", "cede", or "ceed". Thus, it is an object of the present invention to provide a typewriter or text recorder for producing a multi-character signal string identifying one of plural character strings representing word endings which sound the same. The selection is made in dependence upon previously entered characters forming the remainder of the word for which the word ending is desired. Thus, for example, a typewriter or text recorder in accordance with the present invention may have a plurality of word ending keys, each associated with differently spelled word endings, all sounding the same, each key, when actuated, producing the appropriate word ending associated with the previously entered characters. While such word ending writing keys can be keys in addition to those found in the standard keyboard, they can also be incorporated within the standard keyboard by being associated with keys which are infrequently used during text typing. In those cases where the word ending writing key functions are included in the conventional keyboard, a mode key can be provided to the operator to only allow automatic word ending writing when the text recorder is in a word ending writing mode, or to prevent automatic word ending writing when the text recorder is not in a word ending writing mode. On the other hand, such a decision can be removed from the hands of the operator by incorporating within the logic of the text recorder the decision as to whether or not automatic word ending writing is appropriate which decision can also be made dependent upon previously entered keys.
Furthermore, while signals representing different word endings in each word ending group can be generated from a different key, a relatively large dictionary of word endings, some of which sound the same and others of which do not, can be produced by the actuation of a single word ending writing key, the specific word ending produced on actuation of the key being dependent upon the previously entered keys.